I run the pbs in a ct, and setting up a storage in PVE, there's no problem. About the possible chicken and egg issue, as long as you don't want to replace PBS and it's somehow working, you can even have a dupiicate in shutdown state for emergency and start when necessary (I didn't test this). Of course, the datastore physical path must be available for the duplicate, which should be any shareable filesystem or a mount point in the host.